makayla63 makayla63
  • 21-06-2017
  • Mathematics
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Solve by completing the square a^2 + 10a+21=0

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texaschic101
texaschic101 texaschic101
  • 21-06-2017
a^2 + 10a + 21 = 0
a^2 + 10a = -21
a^2 + 10a + 25 = -21 + 25
(a + 5)^2  = 4
sqrt (a+5)^2 = sqrt 4
a + 5 = (+-) 2
a = -5 (+-) 2

a = -5 + 2 = -3
a = -5 - 2 = -7

solution is : a = -3 and a = -7 <==
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